Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($)	Total		Preferred Equity	Common Stock	Surplus		Retained Earnings		Retained Earnings Series C Preferred Stock	Retained Earnings Series D Preferred Stock	Retained Earnings Series E Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2017	$ 3,237,443,000		$ 159,929,000	$ 1,618,000	$ 1,338,722,000		$ 1,934,696,000					$ (62,758,000)	$ (134,764,000)
Comprehensive income
Net income	69,456,000		0	0	0		69,456,000					0	0
Other comprehensive income (loss)	(31,177,000)		0	0	0		0					(31,177,000)	0
Adoption of new accounting standards	(13,738,000)		0	0	0		0					(13,738,000)	0
Comprehensive income	24,541,000
Common stock issued
Stock-based compensation plans, net	10,691,000		0	0	(7,665,000)		20,136,000					0	(1,780,000)
Acquisition of Bank Mutual	481,688,000		0	134,000	390,258,000		0					0	91,296,000
Purchase of common stock returned to authorized but unissued	(26,480,000)		0	(11,000)	(26,469,000)		0					0	0
Purchase of treasury stock	(5,240,000)		0	0	0		0					0	(5,240,000)
Cash dividends:
Common stock ($0.15 per share in 2018 and $0.17 per share in 2019)	(25,710,000)		0	0	0		(25,710,000)					0	0
Preferred stock	(2,339,000)	[1]	0	0	0		(2,339,000)	[1]				0	0
Purchase of preferred stock	(78,000)		(76,000)	0	0		(2,000)					0	0
Stock-based compensation expense, net	3,675,000		0	0	3,675,000		0					0	0
Tax Act reclassification	13,654,000		0	0	0		13,654,000					0	0
Change in accounting principle	84,000		0	0	0		84,000					0	0
Other	771,000		0	0	0		771,000					0	0
Ending balance at Mar. 31, 2018	3,712,699,000		159,853,000	1,741,000	1,698,521,000		2,010,746,000					(107,673,000)	(50,488,000)
Beginning balance at Dec. 31, 2017	3,237,443,000		159,929,000	1,618,000	1,338,722,000		1,934,696,000					(62,758,000)	(134,764,000)
Comprehensive income
Net income	158,648,000
Other comprehensive income (loss)	(57,130,000)											(57,130,000)
Comprehensive income	101,518,000
Cash dividends:
Change in accounting principle												(84,000)
Ending balance at Jun. 30, 2018	3,770,244,000		159,401,000	1,751,000	1,704,587,000		2,070,872,000					(119,888,000)	(46,479,000)
Beginning balance at Mar. 31, 2018	3,712,699,000		159,853,000	1,741,000	1,698,521,000		2,010,746,000					(107,673,000)	(50,488,000)
Comprehensive income
Net income	89,192,000		0	0	0		89,192,000					0	0
Other comprehensive income (loss)	(12,215,000)		0	0	0		0					(12,215,000)	0
Comprehensive income	76,977,000
Common stock issued
Stock-based compensation plans, net	5,456,000		0	0	1,455,000	[2]	(485,000)	[2]				0	4,486,000	[2]
Acquisition of Bank Mutual	6,720,000		0	3,000	6,717,000		0					0	0
Purchase of common stock returned to authorized but unissued	(6,595,000)		0	(3,000)	(6,592,000)		0					0	0
Purchase of treasury stock	(477,000)		0	0	0		0					0	(477,000)
Cash dividends:
Common stock ($0.15 per share in 2018 and $0.17 per share in 2019)	(26,107,000)		0	0	0		(26,107,000)					0	0
Preferred stock	(2,329,000)	[1]	0	0	0		(2,329,000)	[1]	$ 0.3828125	$ 0.3359375		0	0
Common stock warrants exercised	0		0	10,000	(10,000)		0					0	0
Purchase of preferred stock	(459,000)		(452,000)	0	0		(6,000)					0	0
Stock-based compensation expense, net	4,497,000		0	0	4,497,000		0					0	0
Other	(139,000)		0	0	0		(139,000)					0	0
Ending balance at Jun. 30, 2018	3,770,244,000		159,401,000	1,751,000	1,704,587,000		2,070,872,000					(119,888,000)	(46,479,000)
Beginning balance at Dec. 31, 2018	3,780,888,000		256,716,000	1,752,000	1,712,615,000		2,181,414,000					(124,972,000)	(246,638,000)
Comprehensive income
Net income	86,686,000		0	0	0		86,686,000					0	0
Other comprehensive income (loss)	21,597,000		0	0	0		0					21,597,000	0
Comprehensive income	108,283,000
Common stock issued
Stock-based compensation plans, net	7,045,000		0	0	(32,220,000)		0					0	39,265,000
Purchase of treasury stock	(37,467,000)		0	0	0		0					0	(37,467,000)
Cash dividends:
Common stock ($0.15 per share in 2018 and $0.17 per share in 2019)	(28,183,000)		0	0	0		(28,183,000)					0	0
Preferred stock	(3,801,000)	[3]	0	0	0		(3,801,000)	[3]				0	0
Stock-based compensation expense, net	9,397,000		0	0	9,397,000		0					0	0
Other	(293,000)		0	0	0		(293,000)					0	0
Ending balance at Mar. 31, 2019	3,835,870,000		256,716,000	1,752,000	1,689,792,000		2,235,824,000					(103,375,000)	(244,840,000)
Beginning balance at Dec. 31, 2018	3,780,888,000		256,716,000	1,752,000	1,712,615,000		2,181,414,000					(124,972,000)	(246,638,000)
Comprehensive income
Net income	171,347,000
Other comprehensive income (loss)	65,909,000											65,909,000
Comprehensive income	237,256,000
Ending balance at Jun. 30, 2019	3,899,794,000		256,716,000	1,752,000	1,695,715,000		2,288,909,000					(59,063,000)	(284,235,000)
Cash dividends:
Increase Adjustment Options, RSA and RSU					901,000								484,000
Decrease Adjustment Options RSA and RSU							1,000,000
Beginning balance at Mar. 31, 2019	3,835,870,000		256,716,000	1,752,000	1,689,792,000		2,235,824,000					(103,375,000)	(244,840,000)
Comprehensive income
Net income	84,661,000		0	0	0		84,661,000					0	0
Other comprehensive income (loss)	44,311,000		0	0	0		0					44,311,000	0
Comprehensive income	128,972,000
Common stock issued
Stock-based compensation plans, net	827,000		0	0	(211,000)		0					0	1,038,000
Purchase of treasury stock	(40,433,000)		0	0	0		0					0	(40,433,000)
Cash dividends:
Common stock ($0.15 per share in 2018 and $0.17 per share in 2019)	(27,776,000)		0	0	0		(27,776,000)					0	0
Preferred stock	(3,801,000)	[3]	0	0	0		(3,801,000)	[3]	$ 0.3828125	$ 0.3359375	$ 0.3671875	0	0
Stock-based compensation expense, net	6,134,000		0	0	6,134,000		0					0	0
Ending balance at Jun. 30, 2019	$ 3,899,794,000		$ 256,716,000	$ 1,752,000	$ 1,695,715,000		$ 2,288,909,000					$ (59,063,000)	$ (284,235,000)

[1] (b) Series C, $0.3828125 per share and Series D, $0.3359375 per share.

[2] (a) As previously disclosed in Associated Banc-Corp's 2018 Annual Report on Form 10-K, an adjustment was made to the June 30, 2018 stockholders' equity balances related to the grant and vesting of options, restricted stock awards, and restricted stock units awarded. This adjustment increased Surplus by $901 thousand, decreased Retained Earnings $1 million, and increased Treasury Stock $484 thousand. The reclassification had no impact on earnings, expenses, or total stockholders' equity.

[3] Series C, $0.3828125 per share; Series D, $0.3359375 per share; and Series E, $0.3671875 per share.